This invention relates to telescoping conduit and, more particularly, to airtight telescoping rigid conduit attached to an extendable passenger loading bridge, for conveying cabin conditioning air to a parked aircraft.
Over the years, a variety of techniques have been developed for providing ground-based utilities to a parked aircraft. One technique employs portable apparatus which is rolled up to the aircraft, is generally diesel engine powered, and may provide electrical power, high pressure compressed air, or conditioned air to the aircraft. Another technique employs fixed conduit which extends from the airport terminal to a location adjacent the aircraft. The conduit may be used to provide air and electrical power to the aircraft.
Yet another technique for supplying utilities to a parked aircraft employs conduits which are attached to the existing extendable passenger loading bridge used to load and unload passengers. An advantage of this technique is that it utilizes an existing connection system between the terminal building and the aircraft to provide the ground based utilities to the aircraft. An example of this technique is disclosed in U.S. Pat. No. 3,521,316, issued July 21, 1970 to G. J. Adams, et al.
The passenger loading bridge referred to above is of the type having telescoping sections which may be extended and retracted, and which may swing horizontally and pivot vertically. Accordingly, utility conduits attached to the loading bridge must be constructed to accommodate the movments of the bridge. This requirement presents several problems relative to the conditioned air conduit used to provide cabin conditioning air to the aircraft.
Conditioned air is generally provided to the aircraft at very low pressure, on the order of one pound per square inch, and at temperatures different than that of the outside ambient. Conduit used to convey the conditioned air to the aircraft must remain airtight at the low air pressures involved, must be well insulated to prevent temperature loss to, or gain from, ambient, and must present negligible friction and pressure losses through the conduit.
In the past, attempts have been made to employ flexible conduit having an accordian-shaped wall to convey conditioned air along a passenger loading bridge. This type of mechanization is described in the Adams patent referenced above. In practice, this type of conduit produces unacceptably large frictional losses, which increase the amount, and consequently the cost of the power needed to place the air aboard the aircraft.
Prior art designs have also used telescoping tubing having expandable collars which seal adjacent sections of the tubing when high pressure air is applied to the tubing. Because of the high pressures needed to cause the collars to expand, this mechanization is not suitable for low pressure conditioned air. Accordingly, its use has been limited to applications involving high pressure compressed air used for aircraft engine starting and the like, as described in the Adams patent.
Accordingly, it is an object of the present invention to provide new and improved airtight telescoping rigid conduit.
It is another object of the present invention to provide telescoping rigid conduit suitable for conveying conditioned air to an airplane using a telescoping passenger loading bridge.
It is yet another object of the invention to provide telescoping rigid conduit which can accommodate the movements of a telescoping passenger loading bridge, which is airtight at very low air pressure, which presents negligible friction and pressure losses, and which is insulated to prevent temperature loss to, or gain from, the ambient.